1. Field of the Invention
The present invention generally relates to improvements in railroad telemetry and control systems and, more particularly, to improvements in End of Train (EOT) monitoring systems which allow the additional function of checking brake pipe integrity of the train.
2. Description of the Prior Art
Railroads in North America currently use "End-of-Train" (EOT) monitor systems as a means of eliminating the need for cabooses. Current EOT monitor systems, such as Pulse Electronics' "TrainLink II" system, are designed to perform two basic functions. In the first of these functions, the EOT unit monitors brake pipe pressure, motion, and other parameters, and communicates the information via dam radio to the Locomotive Cab Unit (LCU). EOT data communications are initiated at approximately one minute intervals, with no change in monitored parameters, and less than two pound per square inch (psi) change in brake pipe pressure. If parameters change, or brake pipe pressure changes by at least two psi, communication is immediately initiated. Therefore, a rapid brake pipe pressure reduction would result in a series of dam transmissions, approximately one second apart.
In the second function, the EOT monitoring system allows the engineer to initiate an emergency brake application from the LCU to the EOT unit, via the dam radio link. This provides a means of rapidly exhausting the brake pipe from the rear of the train, supplementing normal emergency braking initiated from the locomotive (front) end of the train. It will be observed that this second function differs from the first in that in the first function data is simply gathered by the EOT unit and transmitted to the LCU, whereas in the second function, the LCU transmits a command to the EOT causing it to do something, namely open a brake pipe valve.
End-of-Train monitoring systems have become ubiquitous in trains operating in North America, and there is a continuing process of adding functions to these systems in order to improve the safety and operational control provided.